ES6语法学习笔记(2)-解构赋值

数组解构赋值

let a,b,rest; [a,b]=[1,2]; console.log(a,b);//1 2

…rest数组解构赋值

let a,b,rest; [a,b,...rest]=[1,2,3,4,5,6]; console.log(a,b,rest);//1 2 (4) [3, 4, 5, 6]

对象解构赋值

let a,b; ({a,b}={a:1,b:2}); console.log(a,b);//1 2

解构赋值中的默认值，防止没有配对成功中的undefined

let a,b,c,rest; [a,b,c=3]=[1,2]; console.log(a,b,c);//1 2 3

解构赋值用于变量交换

let b=2; [a,b]=[b,a]; console.log(a,b);//2 1 function f(){ return [1,2] } let a,b; [a,b]=f(); console.log(a,b);//1 2

返回多个值时选择性的接收其中的值

function f(){ return [1,2,3,4,5] } let a,b,c; [a,,,b]=f(); console.log(a,b);//1 4

…用于不确定数组返回的长度为多少，把第一个元素取出，其他的返回一个数组

function f(){ return [1,2,3,4,5] } let a,b,c; [a,,...b]=f(); console.log(a,b);//1 (3) [3, 4, 5]

对象解构赋值按照key:value去匹配

let o={p:42,q:true}; let {p,q}=o; console.log(p,q);//42 true

对象解构赋值使用默认值

let {a=10,b=5}={a:3} console.log(a,b);//3 5

嵌套对象使用

let metaDate={ title:'abc', test:[{ title:'test', desc:'description' }] } let {title:esTitle,test:[{title:cnTitle}]}=metaDate; console.log(esTitle,cnTitle);//abc test //1 4abc test